<template>
  <div>
    <h1>当前求和为：{{sum}}</h1>
    <select v-model.number="n"> <!--.number表示将输入转为数字类型接收-->
      <option value="1">1</option>
      <option value="2">2</option>
      <option value="3">3</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script>
export default {
    name: 'Count',
    data() {
        return {
            sum: 0, //当前和
            n: 1, //用户选的数字
        }
    },
    methods: {
        increment() {
            this.sum += this.n
        },
        decrement() {
            this.sum -= this.n
        },
        incrementOdd() {
            if (this.sum % 2) {
                this.sum += this.n
            }
        },
        incrementWait() {
            setTimeout(()=>{
                this.sum += this.n
            }, 500)
        },
    }
}
</script>

<style scoped>
    button {
        margin-left: 5px;
        margin-right: 5px;
    }
</style>